The MPFC continues to be the flow cytometer of choice for a wide variety of cell biology experiments due to its many unique capabilities, such as: volume sensing, five channels for fluorescence detection, multiple laser excitation, light scatter, and axial light loss on up to three laser beams. Experiments range from cytochemistry to multicolor immunofluorescence, to electronic phenotyping of cells from whole lung digests. And all of the above can be conducted with full sorting capabilities. In addition to the 3 main lasers (2 argon-ion and a krypton-ion), either a dye laser or small HeNe laser can be inserted in front of the 10 watt argon-ion laser for further excitation wavelength diversity. Plans are currently being formulated to modify the existing optical arrangement to provide enhanced sensitivity and resolution when weakly fluorescent probes are used. The first DiDAC system will be installed and tested on the MPFC. We have begun to purchase and assemble the components necessary to add phase sensitive detection to one of the excitation beams on the MPFC. Most of the major components are on hand but we can begin adding the hardware to the MPFC. The necessary physical spaces to add the modulator is available in front of the 10 watt argon-ion laser.